Left: mechanical heating rates applied to the softened particle hydrodynamics (SPH) simulation of a dwarf galaxy (Pelupessy 2005; Pelupessy & Papadopoulos 2009). The maximum heating rate is ~10^-22 erg cm^-3 s^-1. Right: surface heating (Γ_surf) for zero mechanical heating (α = 0) for Z = Z_⊙. The heating rates range from ~10^-22 to ~10^-20 erg cm^-3 s^-1 at n ~ 10³ cm^-3. An SPH particle with n ~ 10³ cm^-3 and a maximum Γ_mech (in the simulation) would have an α = 1 and 0.1 if its G₀ is 1 and 10³ respectively. The black points in the right panel correspond to the boundary points in n and Γ_mech distribution (plotted as open circles in the left panel).